Nupur Malviya

Marker-assisted introgression of resistance to fusarium wilt race 2 in Pusa 256, an elite cultivar of desi chickpea

Fusarium wilt caused by F. oxysporum f. sp. ciceris causes extensive damage to chickpea (Cicer arietinum L.) in many parts of the world. In the central part of India, pathogen race 2 (Foc 2) causes severe yield losses. We initiated molecular marker-assisted backcrossing (MABC) using desi cultivar, Vijay, as a donor to introgress resistance to this race (Foc2) in Pusa 256, another elite desi cultivar of chickpea. To confirm introgression of resistance for this race, foreground selection was undertaken using two SSR markers (TA 37 and TA110), with background selection to observe the recovery of recurrent parent genome using 45 SSRs accommodated in 8 multiplexes. F1 plants were confirmed with molecular markers and backcrossed with Pusa 256, followed by cycles of foreground and background selection at each stage to generate 161 plants in BC3F2 during the period 2009–2013. Similarly, 46 BC3F1 plants were also generated in another set during the same period. On the basis of foreground selection, 46 plants were found homozygotes in BC3F2. Among them, 17 plants recorded >91% background recovery with the highest recovery percentage of 96%. In BC3F1 also, 14 hybrid plants recorded a background recovery of >85% with the highest background recovery percentage of >94%. The identified plants were selfed to obtain 1341 BC3F3 and 2198 BC3F2 seeds which were screened phenotypically for resistance to fusarium wilt (race 2) besides doing marker analysis. Finally, 17 BC3F4 and 11 BC3F3 lines were obtained which led to identification of 5 highly resistant lines of Pusa 256 with Foc 2 gene introgressed in them. Development of these lines will help in horizontal as well as vertical expansion of chickpea in central part of India.

Towards Enriching Genomic Resources in Legumes

Food legumes, mainly comprising dry beans, dry peas, soybean, chickpea, pigeonpea, groundnut, greengram, blackgram, cowpea, lentil and lathyrus, have considerable area under cultivation globally and these are important constituents of cereal-based vegetarian diets. Keeping in view their tremendous importance for diversification and intensification of contemporary agriculture, systematic efforts towards their genetic improvement have been undertaken with classical breeding tools, lately complemented by the use of genomic tools. These genomic tools provide comprehensive information on genes involved in biochemical pathways leading upto nutritional compounds and can be used to understand the genetics of traits of interest and consequently, helping in marker assisted breeding. During the last two decades powerful genetic and genomic tools such as establishment of genetic and physical maps, expressed sequence tags, bioinformatic tools, genome-wide sequence data, genomic and metabolomic platforms, etc. have been developed for many legume species. These efforts have led to development of large scale molecular markers, identification of various marker trait associations, construction of genetic and linkage maps, expressed sequence tags database, partial or whole genome sequences, physical and molecular maps, DNA chips and bacterial artificial chromosome (BAC) libraries. After the genome sequencing of three model species, Medicago, Lotus and Glycine, draft genome sequences have recently been made available in agronomically important food legumes, pigeonpea and chickpea while similar efforts are underway in groundnut and greengram. The new generation sequencing (NGS) and genotyping platforms such as 454/FLX sequencing and Illumina GoldenGate/Solexa have revolutionized plant genomic research as these generate millions of ESTs per run. With the increased amount of genomic resources, there are now tremendous opportunities to integrate these with the genetic resources for their widespread use in routine legume improvement programmes by integrating them with conventional breeding tools. As a result, the genomics assisted breeding (GAB) can now be successfully used in legume improvement and development of improved genotypes having improved agronomic and quality traits and resistance to biotic and abiotic stresses. This chapter discusses the developments made in development of legume genomics and their role in overall improvement of food legumes.

Field characterization of endemic wild Vigna accessions collected from biodiversity hotspots of India to identify promising genotypes for multiple agronomic and adaptive traits

Wild Vigna species possess a reservoir of useful genes that have potential to be utilized in improvement of cultivated mungbean and urdbean. The level of genetic diversity in representative accessions of cultivated and wild Asiatic Vigna species collected from diversity-rich endemic areas of India was investigated using morphological descriptors. Data were recorded on 27 qualitative and quantitative traits in 44 wild and cultivated accessions belonging to 12 Vigna species grown over 2 years and analyzed to compute mean and variances for each trait. Cluster analysis following unweighted pair group method based on arithmetic mean grouped accessions into five clusters with cluster I accommodating most of the accessions. The different accessions showed variation at species level based on morphological descriptors. 3 accessions viz., IC251424 and IC251425 of V. radiata and IC331436 of V. trilobata were superior for multiple traits viz., number of seeds/pod, seed quality and early maturity. Likewise for seed size, IC 298665 of V. unguiculata and PRR 2008-2 of V. umbellata were identified as promising donors while for earliness, 3 accessions of V. trilobata (IC 331545, IC 349701 and JAP/10-7), 1 of V. radiata (IC 251427) and 1 each of V. mungo (IC 251385) and V. unguiculata (IC 298665) were identified as maturing significantly early and therefore, could be used in hybridization programme for introgression of these traits. This evaluation and characterization study on endemic Vigna species provides useful information for improving mungbean and urdbean cultivars through recombination breeding.

Pre- and Post-harvest Management of Physical and Nutritional Quality of Pulses

Grain legumes are consumed in a variety of ways such as boiled whole grains, cooked dal (split grain), powdered and sprouted and in a wide range of snacks. These are extensively used in Asia, Europe and America for gluten-free products, ready-to-eat baked goods, mixes, soups, sauces and other foods along with cereals as one of the ingredients. Nevertheless, major proportion of grain legumes is mostly consumed as natural food products in form of whole grains or dehulled or split grains. Hence, size and shape of seeds, seed coat appearance and its colour, cotyledon colour and grain uniformity are important for trade and commerce. Of late, increasing consumer preferences for healthy and nutritious food have led to greater opportunities for processing, value addition and development of healthy by-products. However, to develop attractive processed foods as well as by-products from grain legumes, their pre- and postharvest management plays an important role. These involve a series of operations which need proper care and maintenance of crop, mechanised production, harvesting and processing and proper storage and disposal of the crop. In recent years technological advancements in processing and value addition provide healthy and nutritious pulse food to the human beings. This chapter describes the food value of grain legumes and their pre- and postharvest management for value addition in enhancing physical and nutritional quality of pulses.

Identification of Subcellular, Structural, and Metabolic Changes Through NMR

Secondary metabolites are unique sources for flavors, nutraceuticals, pharmaceuticals, and industrial bioactive molecules which are biosynthesized in different plant tissues. These metabolites play a major role in the adaptation of plants to the prevailing environment, in overcoming stress conditions, and in defense to several unforeseen invasions. Identifying the biological components and their functions and multiple interactions between components to understand the cellular metabolism of a cell to meet its fluctuating demand for energy and materials has remained a challenging task. Based on traditional metabolic analysis, mapping of intracellular fluxes in metabolic networks is only possible with high-throughput techniques. Nuclear magnetic resonance (NMR) spectroscopy is a powerful and versatile tool that can provide information on the metabolites and their metabolic network. NMR has played a dominant role in the identification of an array of compounds from diverse environments and diverse ecogeographic domains. Plant biotic relationships which include host plant interaction and resistance for an eco-metabolomics have been developed with NMR approach. NMR can also be used to determine low-resolution structures of target–ligand complexes for natively unstructured proteins or membrane proteins that are not amenable to crystallographic approaches.

Role of Molecular Markers

Over the past two decades tremendous progress has been made in the area of genomics of crop plants, especially evolution of large number of high-throughput cost effective molecular markers and genotyping platforms which have helped to identify, map, and introgress alien genes from the wild backgrounds. The alien genes once mapped have been introgressed into cultivated crop plants through marker-assisted backcrossing (MABC) for improving biotic and abiotic stresses in major crop species including rice, wheat, chickpea, cotton, tomato, etc. Molecular markers associated with favorable alien QTL of wild species have an important role in introgression and tracing of these QTL during their transfer into the background of cultivated species. Thus these have become important for exploitation of alien genes in crop improvement. This chapter discusses the role of molecular markers in crop improvement through alien gene transfer.